Polymer Electrolytes in Solid-State Lithium Batteries

Polymer electrolytes offer a promising pathway towards safe, high‐energy‐density solid‐state lithium batteries by combining mechanical flexibility, processability and thermal stability. Research has centred on poly(vinylidene fluoride) (PVDF) and its copolymers as hosts for lithium salts, addressing the intrinsic trade‐off between ionic conductivity and mechanical robustness. Approaches such as phase regulation, incorporation of high‐dielectric fillers and plasticisers, and interfacial engineering with the lithium metal anode have advanced room‐temperature ion transport while suppressing dendrite formation. Emerging materials achieve conductivities approaching 10⁻³ S cm⁻¹, high Li⁺ transference numbers and extended cycling at practical current densities. Such advances underpin development of solid‐state batteries with enhanced safety, long cycle life and the potential for flexible or high‐voltage applications in consumer electronics and electric vehicles.

Research from Nature Portfolio

Recent studies have introduced a phase regulation strategy to produce dense composite polymer electrolytes free of residual porosity. Incorporation of two‐dimensional MoSe₂ sheets into a PVDF matrix disrupts chain symmetry, elevates dielectric constant and optimises salt solvation, resulting in high ionic conductivity and low activation energy. In situ formation of a Li₂Se‐rich interphase on lithium metal enhances Coulombic efficiency and interfacial kinetics, enabling robust cycling at 1 mA cm⁻² and practical full‐cell performance at high rate and loading. Another advance employs a locally solvent‐tethered design in which dimethylformamide ligands are anchored to a Hofmann framework within the polymer host. This ligand‐assisted transport mechanism raises ambient ionic conductivity to 6.5 × 10⁻⁴ S cm⁻¹ and suppresses free solvent degradation at the anode. The composite electrolyte delivers stable Li||Li cycling for over 6000 h and prolonged full‐cell operation with sulphurised cathodes, demonstrating long‐life potential for solid‐state configurations.

Research from all publishers

Composite structures have been engineered to create fast Li⁺ highways in polymer matrices. Layered double hydroxide nanosheets in a poly(vinylidene‐co‐trifluoroethylene) host enforce an all‐trans conformation, immobilise anions and align fluorine atoms to achieve ionic conductivities of 6.4 × 10⁻⁴ S cm⁻¹, Li⁺ transference numbers of 0.76 and dendrite‐free cycling over 1000 h. Embedding oxygenated carbon nitride nanosheets into a PVDF electrolyte delivers a dual benefit: enhanced ionic conductivity (1.6 × 10⁻⁴ S cm⁻¹) and in situ formation of a Li₃N protective layer on the anode. The composite exhibits a wide electrochemical window (5.3 V), fire resistance and stable full‐cell performance at high cathode loading. A third strategy weakens ion–solvent coordination by adding a hydrosiloxane additive to PVDF, forming loosely complexed Li⁺ solvent species and reducing desolvation barriers at ceramic filler interfaces. This promotes rapid ceramic‐involved Li⁺ pathways, achieving conductivities of 7.5 × 10⁻⁴ S cm⁻¹ and record‐long Li||Li symmetric‐cell lifetimes of over 11 800 h, together with high‐rate full‐cell stability.

Polymer Electrolytes in Solid-State Lithium Batteries publication trend

The graph below shows the total number of articles in polymer electrolytes in solid-state lithium batteries across all publications each year (not limited to Nature Index journals).

Technical terms

Polymer electrolyte: A solid or gel medium in which lithium salts are dissolved in a polymer host to conduct ions between battery electrodes.

Ionic conductivity: A measure of how readily ions move through an electrolyte under an electric field, typically expressed in siemens per centimetre (S cm⁻¹).

Li⁺ transference number: The fraction of the total ionic current carried by lithium ions, indicating the efficiency of Li⁺ transport relative to other charged species.

Solid electrolyte interphase (SEI): A passivation layer formed at the interface between lithium metal and the electrolyte that influences interfacial stability and cycle life.

Dendrite: Needle-like lithium metal structures that can form during cycling, potentially causing internal short circuits and safety hazards.

References

1. Phase regulation enabling dense polymer-based composite electrolytes for solid-state lithium metal batteries. Nature Communications (2023).
2. A locally solvent-tethered polymer electrolyte for long-life lithium metal batteries. Nature Communications (2024).
3. Composite electrolyte with self‐inserted structure and all‐trans F conformation provides fast Li+ transport for solid‐state Li metal batteries. InfoMat (2024).
4. Oxygenated carbon nitride‐based high‐energy‐density lithium‐metal batteries. Interdisciplinary Materials (2024).
5. Weakening Ionic Coordination for High Ionic Conductivity Composite Solid Electrolytes. ACS Energy Letters (2024).